// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/disk_cache/blockfile/webfonts_histogram.h"

#include "base/strings/string_piece.h"
#include "base/strings/stringprintf.h"
#include "net/disk_cache/blockfile/entry_impl.h"
#include "net/disk_cache/blockfile/histogram_macros.h"

namespace {

enum WebFontDiskCacheEventType {
    CACHE_EVENT_MISS,
    CACHE_EVENT_HIT,
    CACHE_EVENT_EVICTED_ENTRY,
    CACHE_EVENT_MAX
};

// Tests if the substring of str that begins at pos starts with substr. If so,
// returns true and advances pos by the length of substr.
bool Consume(const std::string& str, const base::StringPiece& substr,
    std::string::size_type* pos)
{
    if (!str.compare(*pos, substr.length(), substr.data())) {
        *pos += substr.length();
        return true;
    }
    return false;
}

const char kRoboto[] = "roboto";
const char kOpenSans[] = "opensans";
const char kOthers[] = "others";

// Check if the given string is a URL for a font resource of Google Fonts.
// If so, returns a label for UMA histogram ("roboto", "opensans" or "others").
const char* HistogramLabel(const std::string& str)
{
    std::string::size_type pos = 0;
    if (Consume(str, "http://", &pos) || Consume(str, "https://", &pos)) {
        if (Consume(str, "themes.googleusercontent.com/static/fonts/", &pos) || Consume(str, "ssl.gstatic.com/fonts/", &pos) || Consume(str, "fonts.gstatic.com/s/", &pos)) {
            if (Consume(str, kRoboto, &pos))
                return kRoboto;
            if (Consume(str, kOpenSans, &pos))
                return kOpenSans;
            return kOthers;
        }
    }
    return NULL;
}

std::string HistogramName(const char* prefix, const char* label)
{
    return base::StringPrintf("WebFont.%s_%s", prefix, label);
}

void RecordCacheEvent(WebFontDiskCacheEventType type, const char* label)
{
    CACHE_HISTOGRAM_ENUMERATION(HistogramName("DiskCacheHit", label),
        type, CACHE_EVENT_MAX);
}

} // namespace

namespace disk_cache {
namespace web_fonts_histogram {

    void RecordCacheMiss(const std::string& key)
    {
        const char* label = HistogramLabel(key);
        if (label)
            RecordCacheEvent(CACHE_EVENT_MISS, label);
    }

    void RecordEvictedEntry(const std::string& key)
    {
        const char* label = HistogramLabel(key);
        if (label)
            RecordCacheEvent(CACHE_EVENT_EVICTED_ENTRY, label);
    }

    void RecordCacheHit(EntryImpl* entry)
    {
        const char* label = HistogramLabel(entry->GetKey());
        if (!label)
            return;
        EntryStore* info = entry->entry()->Data();
        CACHE_HISTOGRAM_COUNTS_10000(HistogramName("DiskCache.ReuseCount.Hit", label),
            info->reuse_count);
        CACHE_HISTOGRAM_AGE(HistogramName("DiskCache.EntryAge.Hit", label),
            base::Time::FromInternalValue(info->creation_time));
        RecordCacheEvent(CACHE_EVENT_HIT, label);
    }

    void RecordEviction(EntryImpl* entry)
    {
        const char* label = HistogramLabel(entry->GetKey());
        if (!label)
            return;
        EntryStore* info = entry->entry()->Data();
        CACHE_HISTOGRAM_COUNTS_10000(
            HistogramName("DiskCache.ReuseCount.Evict", label),
            info->reuse_count);
        CACHE_HISTOGRAM_AGE(HistogramName("DiskCache.EntryAge.Evict", label),
            base::Time::FromInternalValue(info->creation_time));
    }

} // namespace web_fonts_histogram
} // namespace disk_cache
